Harrison M250 Restoration

  1. R-D-R Forum Supporter

    Messages:
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    Derbyshire - England
    Had a bash at another part tonight but failed. This part was fractured and I properly snapped It :dontknow:

    945AD4E4-091B-4760-B9AD-FF00140AB902.jpeg

    Made an interpretation of the part but hit two issues, the internal m6 thread couldn’t Finnish as my cheapo BETA m6 Tap has a rubbish design where the shank is thicker than the Tap so it can’t pass through to form deeper threads. Not the end of the world I’ve ordered a new Tap but the second problem is the internal thread was hand tapped and I must have skewed it as it’s not centric with the piece. So, wait for the tap to come and I’ll make part v2.0

    It’s all an enjoyable learning curve

    5FB07472-0A76-4EC5-85EF-BE4292E656C1.jpeg
    You can see the internal wonky thread here...
    7E73A0AE-AB49-4BEE-BDC5-9433BDA12E62.jpeg
     
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  2. RichardM Member

    start the tap in the lathe next time which will help in keeping it straight
     
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  3. R-D-R Forum Supporter

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    Thanks @RichardM - kicking myself as I've seen that done but didn't put it into practice :ashamed:
     
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  4. Brad93

    Brad93 M J B Engineering

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    Yep see double boosts videos. Centre in the tailstock into the back of the gap.

    Mind you only anygood if your tap has a centredrilled hold in the back.
     
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  5. Pete.

    Pete. Member

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    If not you can wrap some gasket paper round the tap and clamp it tight in the tailstock chuck. The paper will allow it to spin without taking off the numbers.
     
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  6. dobbslc

    dobbslc Forum Supporter

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    Regarding the funny tacho readings, could it be the copex conduit getting a "charge / inductance" from the spinning parts? Is it grounded?
    BTW VERY NICE LATHE!
     
  7. R-D-R Forum Supporter

    Messages:
    1,015
    Location:
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    @dobbslc thats a good thought, in theory it’s grounded as the chassis is grounded and it’s screwed into the chassis. I’ve got to arrange it all properly to mount a terminal box on the back for the light, pump and DRO power feeds. I might experiment whilst I’m at it. It’s definitly just happening whilst the motors braking so something weirds happening in relation to that.
     
  8. Brad93

    Brad93 M J B Engineering

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    It’s back EMF probably.
     
  9. armalites Member

    Messages:
    4,345
    Herefordshire
    If it's noise related then a ferrite core/bead may help. It it only happens when braking I wonder if it just a case that the tacho is truggling with the change in speed and is assuming an error condition because it's trying to avergae out a reading. From the video when it spins up it looks like it settles on one speed then jumps to a higher one when in theory you would expect it ramp all the way up so it may well just the way that tacho samples.
     
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  10. Carl Wilson Member

    Messages:
    1,501
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    Moray
    Re holding the tap in the tailstock chuck. Great use for the jog function on your vfd. Good for starting taps or power tapping.
     
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  11. Carl Wilson Member

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    1,501
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    It's all looking really good. Nice to see that you are also going with the CT90 cutting oil product placement!
     
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  12. Carl Wilson Member

    Messages:
    1,501
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    I've started a trend! First time for everything.
     
  13. slim_boy_fat

    slim_boy_fat Forum Supporter

    Aye, it's ALL your fault! :D
     
  14. R-D-R Forum Supporter

    Messages:
    1,015
    Location:
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    Thanks

    I'm starting to think its definitely interference, I played more tonight if you watch the video and listen to the sound you can hear the lathe stop spinning but the noise of whatever the VFD is doing with the motor overrunning a few seconds, as soon as this noise stops the Tacho Zeros. It is doing something as the speed ramps up, it has a short pause and then catches up but not sure thats a problem more by design of how it calculates. Not a massive issue but I'm going to try and get to the bottom of it, ill try a ferrite filter I can pinch one off a spare power adapter.
     
  15. Carl Wilson Member

    Messages:
    1,501
    Location:
    Moray
    Well I just hope RDR is more successful than me. I'm still waiting for my IBC container of CT90 to arrive.

    I think the behaviour of the tachometer is noise related too. Mine doesn't do that, but it is sometimes slow to respond if you ramp the speed up and down quickly. I put that down to there only being one pulse per rev input to the counter.
     
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  16. R-D-R Forum Supporter

    Messages:
    1,015
    Location:
    Derbyshire - England
    Picked up a LoVo-Lite this week. Needs refurbishing but is all intact by the looks of it with nice swivel actions. Needs all new wiring and painting. Can anyone point me to where the Light is normally attached on the M series lathes. I had it in mind there were mounting holes on the back of the headstock but just looked and there isn't :dontknow:

    IMG_2041.jpg

    IMG_2043.jpg
     
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  17. Brad93

    Brad93 M J B Engineering

    Messages:
    6,605
    Location:
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    On my 140 it mounts to the back of the headstock with 3 button head slotted screws.

    Although for your machine I think I would of gone for something more modern like this https://uk.rs-online.com/mobile/p/machine-lights/0600723/
     
  18. Carl Wilson Member

    Messages:
    1,501
    Location:
    Moray
    DSC_1696.JPG Hello RDR. That light is the same one that is fitted to my Harrison Mill. I believe it's also the same as the ones fitted to the L5 etc lathes. On my mill the light is bolted to a pretty chunky 50 volt transformer that runs it. It got a bit bent after the incident in the back of the lorry.

    On my M250 the light is a slightly different design. It is also bolted to the top of a boxed transformer. The whole is then bolted to the back of the headstock, pretty much centrally above the motor.

    I'm away working just now but I tried to find a picture where you could see the transformer for the light. The light is fixed on top of this. You can just about see it in the above picture.
     
  19. R-D-R Forum Supporter

    Messages:
    1,015
    Location:
    Derbyshire - England
    Thanks Guys I thought they went on the back of the headstock, I'll have another poke around for some holes I didn't fill anything when I was restoring it.

    This is an older type of light, I was looking around for something in keeping and made a cheeky offer as it needs a complete rewire which was accepted :-) Ill be putting a suitable holder and LED bulb in it using a 240V toggle switch in keeping with the original meaning I won't need the transformer box. Will look to fabricate something to hold it off the back of the Headstock. I'm thinking ill use the last of my Harrison Beige for the arms with the black bits fresh Matt hopefully will look fitting for the lathe when done.

    If you had asked me 2 months ago the light would be the last on my list but on using it even with lighting above I struggle at times to see the detail in what I'm doing.
     
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  20. Carl Wilson Member

    Messages:
    1,501
    Location:
    Moray
    Here is my circa mid 1960s Harrison Mill with a slightly bent looking light that is the same design as yours.

    Nice idea to update the light with an LED. I find it is really useful especially for boring or any other sort of internal work.
    IMG-20180402-WA0030.jpeg
     
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